Hard floor cleaning these days is done by first vacuuming the floor, followed by mopping it. Vacuuming removes the coarse dirt, while mopping removes the stains. From the state of the art many appliances, especially targeting the professional cleaning sector, are known that claim to vacuum and mop in one go. Appliances for the professional cleaning sector are usually specialized for big areas and perfectly flat floors. They rely on hard brushes and suction power to get water and dirt from the floor. Appliances for home use often use a combination of a hard brush and a squeegee nozzle. Like the appliances for the professional cleaning sector these products use the brush to remove stains from the floor and the squeegee in combination with an under-pressure to lift the dirt from the floor.
Said squeegee elements are usually realized by a flexible rubber lip that is attached to the bottom of the cleaning device and merely glides over the surface to be cleaned thereby pushing or wiping dirt particles and liquid across or off the surface to be cleaned. An under-pressure, usually generated by a vacuum aggregate, is used to ingest the collected dirt particles and liquid.
A squeegee device for a vacuum cleaner system is, for example, known from EP 0 576 174 A1. A sweeper that uses an above-mentioned combination of a brush and a squeegee is, for example, known from U.S. Pat. No. 7,665,172 B1. The power floor sweeper described therein comprises a foot assembly with a motor driven primary agitator and a pair of edge agitators coupled to wheels such that manual propulsion of the sweeper rotates the wheels and thereby the edge agitators. The sweeper, however, does not include a vacuum source and is therefore not able to pick-up water from the floor to be cleaned. The performance on drying the floor is thus rather low.
Another vacuum cleaner that is known from the prior art and also uses a combination of a rotating brush and a squeegee is known from U.S. Pat. No. 4,864,682 A. This vacuum cleaner comprises a self-adjusting wiper strip assembly that automatically adjusts for the type of floor surface on which the vacuum cleaner is being used. The assembly used therein requires a high suction power in order to receive a satisfactory cleaning result. The brush which is used in this vacuum cleaner is an agitator (also denoted as adjutator) with stiff brush hairs to agitate the floor, e.g. a carpet. These stiff hairs show a rather good scrubbing effect, which enable to use the brush particularly for removing stains. However, the performance on drying the floor is rather low, since such an agitator is not able to lift liquid from the floor.
Vacuum and mop in one go devices known from the prior art often use brush elements that are actively sprayed with water or a cleaning rinse in order to improve the removal of stains. Such devices usually use a double squeegee element having two squeegees that are arranged on one side of the brush, as this is exemplarily shown in the attached FIG. 12. An additional vacuum source generates a suction in a channel between said double squeegee arrangement in order to remove the cleaning water from the floor again.
However, in order to remove the actively sprayed cleaning water from the floor again these devices always have to be moved in a forward direction in which the brush is, seen in the direction of the device movement, located in front of the double squeegee arrangement. Moving the device in an opposite backward direction would leave the floor wet, since the cleaning water which is dispersed with the brush is not removed from the squeegees in this backward stroke.
To get a good cleaning result in a forward as well as in a backward stroke of the device known cleaning devices are therefore provided with a double squeegee nozzle on both sides of the brush. Such an arrangement is exemplarily shown in the attached FIG. 13. Even though such double squeegee arrangements on both sides of the brush show good cleaning results, the nozzle of these devices become fairly bulky. This again results in a non-satisfying, limited work capability. Especially in household appliances where often narrow corners need to be cleaned, such bulky nozzles are, due to their limited liberty of action, uncomfortable to use.
Besides that, the use of double squeegee arrangements as shown in the attached FIGS. 12 and 13 has several further disadvantages. Due to the constant contact of the squeegees with the floor during the movement of the device, such double squeegees may generate a high scratch load to the floor. Especially when the double squeegee arrangements are used on each side of the brush (see FIG. 13), this will lead to an increased risk of inducing scratches on the floor. Furthermore, such squeegee arrangements include the disadvantage that they are not open for coarse dirt like e.g. hairs or peanuts, since coarse dirt is often entangled within the squeegees or pushed away from the squeegees, and is thus not able to enter the suction inlet. This situation is shown in the attached FIG. 15 in a schematic way. Therein, reference numerals 90 and 90′ denote the two squeegees. If, during the movement of the vacuum cleaner, the squeegee 90′ approaches a coarse dirt particle 92, this particle will be entangled in front of the squeegee 90′ and will not be able to enter a suction area that is defined in the space between the two squeegees 90, 90′, since the squeegees are in constant contact with the floor. Apart from that, such double squeegee nozzles are hard to clean and do not have the ability to clean themselves.
In order to overcome these disadvantages other devices known in the art use two separate brushes that are arranged in parallel to each other (schematically shown in attached FIG. 14). A cleaning device of this kind is exemplarily known from U.S. Pat. No. 1,694,937. Said document discloses a floor scrubbing machine, which is capable of picking up dirt from a floor by two cylindrical floor brushes disposed parallel and close together. These brushes rotate at high speeds, one running clockwise and the other one counterclockwise. In this way, the adjacent peripheries travelling together with a sufficiently high velocity to project the dirt vertically upwards with a considerable force in the form of a substantially flat jet. A wiper or a squeegee is applied in addition to the brushes in order to dry the floor. Due to the two separate brushes and the additional squeegees the nozzle becomes also according to this solution fairly bulky, which again ends up in a non-satisfying liberty of action for the consumer.